1. Field of the Invention
The present invention relates to a dry load test apparatus used in an electric load test of, for example, AC generator, other power supplies and the like.
2. Description of the Related Art
 less than Necessity for Load Test of Private Generator greater than 
Recently, in facilities (buildings) requiring power such as factories, department stores, computer center buildings, medical facilities and a commercial buildings, it is desirable that stable power supplying can be achieved even in a power failure. For this reason, for the facilities that requires such power, a private generator such as a three phase AC generator is provided, and in a power failure, the private generator is driven urgently to supply power into the facilities so that stable power supplying has been performed even in a power failure.
Such a private generator is not always operated but limited to use only in an urgent power failure so that it is required to operate certainly in such cases. For this reason, it is required to perform the load tests periodically in order that the private generator can be operated normally in an urgent power failure.
The best method for load tests for the private generator is practical operating to generate power and supply the above mentioned generated power to apparatuses practically using power (electric apparatuses, such as an interior illumination and a cooler) in factories or department stores. But, if load test takes long time and there are tens of times of ON/OFF power supply tests implemented and sudden rising up test of power capacity, it is difficult to perform the load test by using an apparatus requiring practically power (for example, electric apparatus such as an interior illumination and a cooler), and the apparatus is not appropriate for the test.
Therefore, practically, the load test for private generator has been performed using a load test resistor comprising a load resistor having capacity apt to the capacity of generator.
 less than Conventional Example of a Load Test Apparatus greater than 
Further, a three phase AC generator has been used in the above mentioned private generator. Hence, in the dry load test apparatus disclosed in Japanese Patent Laid Open No. Hei 6-34725 publication or Japanese Patent Laid Open No. Hei 7-43436 publication, three fixed resistor units which are star connected are used to obtain the load corresponding R-phase, S-phase and T-phase of the three phase AC generator.
Besides, each of the fixed resistor units has a resistor assembly comprising a plurality of bar shaped resistor elements, and load capacity is set with combination of the plurality of resistor elements.
Moreover, besides the apparatuses disclosed in the publications, there are apparatuses that switching settings of load capacity for load test can be available. For example, those are disclosed in Japanese Patent Laid Open No. Hei 9-15307 publication, Japanese Patent Laid Open No. Hei 9-15308 publication, Japanese Patent Laid Open No. Hei 9-15309 publication and the like. In the apparatuses disclosed in the publications, a large number of resistor assemblies consisting of a plurality of bar shaped resistor elements are prepared, and the large number of resistor assemblies are disposed in the upper and lower with multi stages so that a load resistor circuit is formed from the large number of resistor assemblies. Further, by the switching combination of the multi stage resistor assemblies, resistance value of the load resistor circuit can be changed.
Further, a load test resistor apparatus to which switching selection means for selecting the above mentioned resistance value of the load resistor for load test is provided is disclosed, for example, in Japanese Patent Laid Open No. 2000-19231 (P2000-19231A) publication.  less than   greater than 
 less than Load Test Apparatus for a Movable Type Three Phase AC Generator greater than 
However, in the resistor apparatuses for load test of the three phase AC generator, there are a permanent type one which is permanently established is such as factories, department stores, pumping facilities, hospitals and the like and movable type one which is mounted on a vehicle and is carried to use in the facilities which needs the load test only when the load resistor test performs. For example, the movable type load test apparatus is that a dry load test apparatus 3 is mounted on a carrier 2 of a truck 1, as shown in FIG. 50A (refer to Japanese Patent Laid Open No. Hei 9-15307 publication).
The dry load test apparatus 3 has the frame 4 attached to the carrier 2, and R-phase, S-phase and T-phase resistor units 5, 6 and 7 adjacently attached to the frame 4. Each of the resistor units 5, 6 and 7 has the same configuration.
Each of the resistor units 5, 6 and 7 has a base frame 10 disposed on the frame 4, a vibration isolation rubber 11 interposed between the frame 4 and the base frame 10, and fixing nuts 13 and 14 which are screwed to the frame 4, the base frame 10, the vibration isolation rubber 11 and a fixing bolt 12, and both ends of the fixing bolt 12, as shown in FIG. 50B.
Further, each of the resistor units 5, 6 and 7 comprises an electric fan 15 disposed below the base frame 10 and the frame 4 and attached to the frame 4, the isolator (isolation member) 16 fixed on the base frame 10, the housing 17 fixed to the isolator 16 and opened at the upper and lower ends thereof, and the hood 18 which guides cooling wind from the electric fan 15 to the housing 17. As shown in FIG. 51, the housing 17 has a structure that side face openings of the frame 18 having a hexagonal shape formed with angles are closed with isolation plates 19a, 19b, 19c and 19d. 
Also, each of the resistor units 5, 6 and 7 has the resistor bodies 20R, 20S and 20T disposed in the housing 17. The resistor bodies 20R, 20S and 20T have the resistor assemblies Ri, Si and Ti [i=1, 2, 3 cn] disposed in the upper and lower with multi stages. As shown in FIG. 51, the resistor assemblies Ri, Si and Ti have a plurality of bar shaped resistor elements (heaters) 21 which are provided side by side on the plane and the both ends thereof are held on the isolation plate, and an electrically conductive connection piece 22 to which the plurality of resistor elements 21 are serially connected.
Besides, as shown in FIGS. 52 and 53, the resistor assemblies Ri, Si and Ti of the resistor units 5, 6 and 7 are connected to a main vacuum circuit breaker (main VCB) MB which is a high voltage switch through separate vacuum circuit breakers (separate VCB) Bi [i=1, 2, 3 cn] which are high voltage switches.
In such a manner, the multi stage resistor assemblies Ri, Si and Ti can be turned ON/OFF with the separate vacuum circuit breakers (separate VCB) Bi so that fine load introducing test of three phase AC generator can be performed.
That is, in such a configuration, the sequence for performing the load resistor introducing test of the three phase AC generator 23 are as follows.
First, the operation of the three phase AC generator 23 is started, and then, the main vacuum circuit breaker MB is operated to be ON. Next, some of numerous separate vacuum circuit breakers (separate VCB) Bi are operated to be ON. In this case, for example, a few of the large number of separate vacuum circuit breakers (separate VCB) Bi are operated to be ON by every 10 minutes, thereby the load for the power generation capacity of the three phase AC generator 23 being 25% for the first 10 minutes, 50% for next 10 minutes, 75% for next 10 minutes, and 100% for the final 10 minutes. By such a predetermined time interval, the data from the load test of the three phase AC generator 23 are taken with changing the ratio of the load for the power generation capacity of the three phase AC generator 23 changed, thereby the fine load introducing test of the three phase AC generator being performed.
However, since the high price vacuum circuit breakers (VCB) Bi are provided at each of the resistor assemblies Ri, Si and Ti [i=1, 2, 3 cn], it causes drastic price increase of the dry load test apparatus. Further, in case where the vacuum circuit breakers (VCB) Bi and the resistor assemblies Ri, Si and Ti [i=1, 2, 3 cn] are connected to cable in consideration of ensuring potential between poles and withstand voltage and the like, a disposition interval W between the connection cable and the vacuum circuit breakers (VCB) Bi should be more than 10 cm. As a result, the resistor apparatus itself should be very large.
Therefore, the object of the present invention is to provide a dry load test apparatus which can be set resistance value of load resistor for load resistor test finely and whose manufacturing cost can be lowered.
In order to achieve the object, a dry load test apparatus according to the first aspect of the present invention is characterized by comprising multi stage resistor bodies for high voltage load test having numerous flat shaped resistor assemblies consisting of numerous elongate resistor elements provided side by side in a flat shape with interval and serially connected at an end thereof, said numerous resistor assemblies being provided side by side with multi stages with interval in order that flat planes thereof become parallel so that numerous resistor element columns which are formed with corresponding said resistor elements of the multi stage resistor assemblies are provided; a plurality of first multi stage switching members, one end thereof being connected to an end of each of said resistor elements of the resistor element columns to constitute switching member columns; numerous inter assembly conductive members respectively connecting other ends of first switching members of said switching member columns one another; and a high voltage switch connecting a few of said large number of inter assembly conductive members to an under test power supply.
Also, the dry load test apparatus according to the second aspect of the present invention, in addition to the first aspect, is characterized in that one end of said first switching members is connected to each ends of at least a few of said resistor elements of the resistor element columns to constitute the switching member columns.
Further, the dry load test apparatus according to the third aspect of the present invention, in addition to the first aspect, is characterized in that one end of said first switching members is connected to each ends of all of said resistor elements of the resistor element columns to constitute the switching member columns corresponding to each of said resistor element columns.
The dry load test apparatus according to the fourth aspect of the present invention, in addition to the first aspect, is characterized in that a shorting means for shorting selectively said large number of inter assembly conductive members one another is provided.
The dry load test apparatus according to the fifth aspect of the present invention, in addition to the fourth aspect, is characterized in that said shorting means is a second switching member.
The dry load test apparatus according to the sixth aspect of the present invention, in addition to the fifth aspect, is characterized in that wherein said switching member comprises one set of a plurality of stationary contact pairs as the first and second stationary contacts, a plurality of movable contacts interrupting or connecting the first and second stationary contacts of each of said stationary contact pairs, and a driving means driving said movable contacts to the first and second stationary contacts in advance or retreat simultaneously to interrupt or to connect the first and second stationary contacts of each of said stationary contact pairs; and wherein said plurality of first stationary contacts and said second stationary contacts are individually connected each other.
The dry load test apparatus according to the seventh aspect of the present invention, in addition to the sixth aspect, is characterized in that said driving means are solenoids which are operatively controlled by a control panel and a control circuit.
The dry load test apparatus according to the eighth aspect of the present invention, in addition to the seventh aspect, is characterized in that said solenoid comprises a coil and an actuator driven by magnetic force of said coil, and wherein said solenoid is disposed on the substantially same straight line as a driving direction of said movable contact.
The dry load test apparatus according to the ninth aspect of the present invention, in addition to the sixth aspect, is characterized in that said driving means is an air cylinder which is operatively controlled by an air control circuit.
Moreover, the dry load test apparatus according to the present invention means a dry electric load test apparatus. That is, the dry load test apparatus does not cool a resistor element as a load generating heat with water, but cool it with dry air. Hereinafter, the dry load test apparatus is used as the meaning.